Combination master cylinder and power brake valve



Feb- 23, 1954 c. E. DEARDORFF ETA'L 2,670,004

COMBINATION MASTER CYLINDER AND POWER BRAKE VALVE Filed April 28, 1952 S nm om, mm mm mm m xm@ 5mm :v//QW QNQQ@ H mm v* I f rf mv 2?/ n@ R mv vm mvo. 7 mn mm m/ mv Nm vm. mm., mm E m wv INVENTORS NN mN ATTORNEY Patented Feb. 23, 1954 COMBINATION' MASTER.l CYLINDER' 'AND POWER vBRAKEVALVE Clinton'EDeardorL-, Sepulveda., William E: Elder;v

Sherman Oaks;t and Natalen;l Bifano, Los AAn.-n

.'geles, Galif.,uassignors to Bendix-Aviation Cor.- poration, NorthHo1lywo0d,. Cal-if., a corpora? ti'on olf-,Delaware This invention relates to hydraulic brake-syst tems and more particularly to the masterlcylinder endg-thereof:which/,applies orzcontrolsithefapplcationzof Ypressure iiuidfto thelbrakel-ines.: More specifically, the.;inventionarelatesf .to that: type .of mastericylinder fandvvalve.assemblythat normally acts .as af powenbrake. valve tcontrolfthe appli catoirkotv fluid;- from a.' power pumpor. othen sep.- aratezrpressureesourcefto.:the.brales; but which, .in eyent' :.of failure;- of the .fseparatet pressure source, automaticalglyfactspas' a master-..cylnder to `supplwpressure :fluid Idirectlyyto the brakes:v4

Anfobjecttof the-inventionis to provide. anfassembly of, the type: described that is. relatively simple,A andfpracticablefto manufacture 4.and has lttlefleakage f @then more. speciiicJ obj ectshandrfeatures ...oft-the invention VWillfbe apparent from `the .description toffollow withzreference. to. the drawing.

The; single. iigure of the. drawing. is alongitufdinal; sectional. vievvvthrough-.ant assembly., in. ao: cordance-.-W-itn thefinvention..

Referring to the drawing,..theunitrtherein,.ds= closedrcompri-ses abody I Whichdeiines amaster brakacylinder. II,.a..controLfcylinder, |21 andla transienvalvecylinder. I3.. The .master cylinder I...I has a..fluid,. inlet port. I4. adapted lito be conf nected .to aA ud. reservoir. The body.. IU'is adeA ditionally provided. Witha pressure port'. I5',.are turnrport. IE,..and, a. brake, port'. ITI'.v Tle pressure port |.5. may-bev supplied.' Witli. fiiiidby Aa pump which..draws.flud.l from `the samereservoirr to,

Whichport. IAffis. connectedl, Thareturn port, I 5' may,.return,to. the` same reservoir. Tl'ie .brake p ortIlTis `connectedt'o the brake line leading to the brakes tobe .actuat'ed The master. cylinder Il" contains a piston` 20' which is normally -rnaintained' inleftmost' posi?- tion'by a helical" compression spring"2"|but"can begsliiftedlto 'the rigl'it; against theforcel' exerted b'ythe spring' 2 I';A by a; piston` rodi22 which 'extends'through a sealedaperture inthe right" end oft'tlie*'cylinder'r I=I-" toV the' exterior. I'liepiston'` 20contains a'checkvalve inthe'form-of afball"2`3l urgedagainst44 aseat` 24 'by a'- spring-25v During ri'gl'it'vvard-movement ofthe piston` 2 0 the b'a'll'2 3'- seats against the seat 24 to,prevent-flow'offiiuidl through 'thejpistonsof-tliat 'fluid is displaced from the rightendi'of the'cylin'd'erfll through a control passage" '206C and" `fresh" fluid is drawn in through theport I4. When the.. piston 20 isre turned'to the left,l the check valve 23' may open to permit aentry. offuidlinto the riglit2end of the cylinder-vll. When the piston 20 yis in itspos.-4 tiem oiarest in the left endfoflthewcyindere II,; as showmgthaball. 23 is heldaoilitszseat byfaiastop 2EA der lil. Thisrinsures t at-fall pressure,l will be relieved' in :the: 'cylinder I II and;l theffcontrol:v pas-f sage@y 2161i when; thezfmasterpiston l 2.0 .is inf its,- .posi. tion ofrestzx `IElluidi deliveredffromzthefmaster cylinder-,LI

through the control passage 26 enters the: Aright end-.of .the transfer:valvercylinderf I3: through a control port 29. This. transfert-Valve' cylinder I3 contains asleeve pistomS-f-:Whichr isfreciprocable in` the cylinderand' has -for-med. on? its f rightn end afpoppet'fheadl 3-I Whichris positioned' .in anf.an nularwgroovezZ iny thefcylinder I3.; The-piston sleeve 30- is reciprocablefbetvveen a'rightmost?po-` sition; as shown, in which: the` poppet 34m-seats against the-1ightfedgev otthefannular groove:v 3.2; into ra leftmost positionvinhzwhich the,-poppet-..3l 'seals againsty the-l left'f edgev of-f the` recess- 32.-, It will loeA observed" that f the recess-` l32;- isx directly connectedato .thebra'kaportr I'L. The surfacefofthefpistoniS isre'cessed, tocftheleft-,of the-.poppet 3 I-, .to define'wthw the; cylinder. IBY-anfannular recess 34 .-1 which is.; connected by;1 a: delivery lpassagef35 toa valvecy-linder Which'constitutosa part of the powerfbrakefvalve-portionlofsthecomeplete assembly. TheVv cylindrical;bore.z 38; ot.Y the piston sleevefflllV contains#y `afpistondl) which is connected by a stem4l toy a-poppet 42=-Whichis 'adapted to reciprocate,A into and .out offfenaage-l ment v'-With the right:l end.' of i the esleeve: piston- 3,02 The piston.4 and.A poppet assembly.. is-. urged-tozthe left by a .helical compression=spring43ocompressed between'.- thepoppet142 and -tan .endcap [.441 for :the cylinder |13.-r The portion/off the: sleevel piston bore-tato' theright of thee-piston 40:'isf; communi--y cated by ports 45: with ani annular 'recess-.-46;.fin the-- cylinder 1.3rwhich is= connected `by'a control passageflt .with the-right: end.: off the control cyl@ inder I2. The left end.of=thertransferrvaive `cylin'der' I 3;' iszconnectedby.'azpassagez 50 to; a1 .pressure .chamber`A` 5I Which is:l in.,` turn connected? to the pressur.e1port" I 53 It willbe observed' thatzwliateverf pressure'ex` i'stlssin thepressureport I5@ is appliedl ati alltimes through-the pressure-passage 50-to* the left end ofV the pistonr sleeve 30 fand" the left: end of' the pisL ton 40. This-:pressure is normally'greater"tlan thepressure' present-in the controlfportz)` which acts againstitheright endof'the piston sl`eeye3l0l 'andthe piston 40'. .Hence thepiStOn sleeve-.Ellis normally inJ its.rightmost'.;positiomin..which:the.. puppet .31, sealsagainst the right cedge,oi.i'.l1e.-=an'.- n-ular grooveZf. and;A .the 'pistonfdfvisin itsrfghtfmost 1 osition.inwhichmliev poppeti .is.:op,.enedl away from, the. rig-ht .end ortho .piston L4sleeve` 31).;v Whenlihemasterrpiston. rodJfZfismeciprocated to; pumpiiuid; through thegpassage ZI-zthisf Huid-1% free to flow past the poppet 42 and through the bore 38 of the piston sleeve and through the ports 35 and the passage 48 into the right end of the control cylinder I2. At the same time, the brake port I'I is connected through the delivery passage 35 to the `cylinder 36.

The control cylinder I2 contains a control piston 52 which is coupled by a compression spring 53 with a plunger 54 which is reciprocable in the cylinder 33 and has an axial uid passage 55 extending therethrough which passage is adapted to be closed by a poppet valve 53. The left end of the cylinder 36 is closed by a closure member 5l dening at its left end a valve seat 58 communicating with the pressure chamber 5|. A poppet El! is adapted to seat against the seat 58 and is connected by a stem EI to the poppet 56. A stem 63 extends from the left end of the poppet SQk into a guide passage E3. A helical compression spring B5 compressed between the poppet SD and the closure member urges the poppet 60 against its seat 58 to normally disconnect the pressure chamber 5I from the cylinder 33.

The plunger 54 is normally urged to the right by a, helical compression spring 'I into a position in which the poppet 56 is clear of the bore 55, so that the cylinder 35 is connected to the control cylinder I2, which in turn is permanently connected to the return port I6. When pressure uid is admitted to the right end of the control cylinder I2, it urges the control piston 52 therein to the left, which compresses the spring 53 and moves the plunger 54 to the left until it engages against and seals with the poppet 53 thereby disconnecting the cylinder 36 from the return port I6.` Further leftward movement of the plunger 54 carries the poppet 53 with it and moves the poppet 5!) clear of the seat 58 to admit pressure fluid from the pressure port I5 past the poppet 6I) into the cylinder 36 and thence through the delivery passage 35.

The system disclosed operates as follows:

As previously indicated, actuation of the master cylinder piston rod 22 delivers fluid through the control passage 26 and the control port 29 into the right end of the transfer valve cylinder I3 from whence it flows past the poppet 42 and through the sleeve piston bore 33, the ports 45,

and the passage 138 into the right end of the control cylinder I2.

This moves the control piston 52 to the left, to cut off the cylinder 35 from the return port I5 and connect it to the pressure port I5 to admit pressure uid through the passage 35 and the annular recess 34 to the brake port I 'I to actuate thebrakes.

Now let it be assumed that the pump applying pressureiiuid to the port I5 has failed and that the pressure in the port I5 drops toa low value relative to the pressure developed in the master cylinder II when the piston 20 therein is moved to the right. The force of the spring 43 and the pressure force of the fluid from the master .cylinder acting on the right end of the sleeve piston 36 and the piston 40 is no longer opposed by the high pressure formerly existent in the left end of the transfer valve cylinder I3. Hence, the sleeve piston 3D moves to the left until the poppet 3| seats against the left edge of the groove 32, and the piston d moves to the left until the poppet 42 seats against the right end of the sleeve piston 30. The closure of poppet 42 against the right end of the sleeve piston 30 breaks communication between the control port 29 and the right end of the cQtltIQl cylinder I2 so that uid can no longer ow from the master cylinder II to the control cylinder I2. The shifting of the poppet 3| from engagement with the right edge of the groove 32 to engagement with the left edge thereof disconnects the delivery passage 35 from the brake port I'I and connects the control port 29 to the brake port I'I. Thereafter all fluid delivered from the master cylinder through the passage 26 flows directly through the brake port I'I and through the brake line to the brakes, so that the device functions as an ordinary master cylinder instead of as a power brake valve.

Although for the purpose of explaining the invention, a particular embodiment thereof has been shown and described, obvious modifications w'ill occur to a person skilled in the art, and I do not desire to be limitedto the exact details shown and described.

We claim:

1. In combination: a power brake valve having a power pressure port, a delivery passage, an exhaust port, a control passage, a control motor connected to said control passage, valve means actuated by said control motor in response to a varying pressure in said control passage for selectively connecting said delivery passage to said pressure port or to said exhaust port; a control port and a brake port; and pressure responsive transfer valve means diierentially responsive to pressures in said pressure and said control ports respectively for connecting said control port to said control passage and said brake port to said delivery passage when the pressure port pressure exceeds the control port pressure, and disconnecting said deliveryV passage from said brake port and said control passage from said control port and connecting said control port directly to said brake port when the control port pressure exceeds the pressure port pressure.

, 2. The combination of claim ,1 in which said transfer valve means comprises: a cylinder connected at one end to said control port and at the I other end to said pressure port and having an annular groove adjacent said one end connected to said brake port; a sleeve piston in said cylinder having a double faced annular poppet head on its one end positioned in said annular groove and reciprocable to seat adjacent one or the other edge of said annular groove; a piston reciprocable in said sleeve piston adjacent the other end thereof, and a poppet connected to said piston for reciprocation therewith against and away from said one end of said sleeve piston; said cylinder and sleeve piston denning an annular recess on the pressure port sid-e of said groove and connected to said delivery passage; and ports in said cylinder and sleeve piston communicating said control passage with the interior of said sleeve piston intel'- mediate the piston therein and said one end.

3. The combination of claim 2 including spring means urgingsaid poppet against said oneend of said sleeve piston.

CLINTON E. DEARDORFF. WILLIAM E. ELDER. NATALE J. BIFANO.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,472,695 Chouings June 7, 1949 2,501,941 Hallerith Mar. 28,1950 2,569,028 Stryker Sept. 25, 1951 

